Photographic dusting-on process by the employment of acetals as the light-sensitive material



' I l I I I I I 1 x V 1 r Aug. 17, 1937. G. KCfiGEL 2,090,450

PHOTOGRAPHIC DUSTING ON PROCESS BY THE EMPLOYMENT OF ACETALS AS THE LIGHT'SENSITIVE MIUIERIALJ Filed Nov. 29, 1955 zgght aemzltz're layer fbr'med of an metal of an, aromatic ndtro aldehyde of the benzene series and a yoaiyk ydrz'c a'dco/zad support Gustav K0" INVENTOR WWW H18 ATTORNEYS 25 are obtained a'sjthe case may be.

Patented Aug. 17, 1937 UNITED STATES PHOTOGRAPHIO DUSTING-ON PROCESS BY 7 THE EMPLOYMENT OF ACETALS AS THE LIGHT-SENSITIVE MATERIAL Gustav Kiigel Baden-Baden, Germany Application November 29, 1935, Serial No. 52,198

1 In Germany December 3, 1934 8 Claims.

- The present'invention relates to a photographic dusting-on process and light sensitive materials to be employed in this process.

An object of the invention is-a process for the production of prints or other contrast efiects according to the dusting-on process. The process according to the invention is capable of employment in many directions. It can be employed for the production of photographs after 10 the manner of the carbon printing process, also again for ceramic, galvanic, ehemico-graphic and other purposes. Furthermore, it is possible, according to the process, to produce part negatives formulti-colour photography. Other objects of the invention are light sensitive materials comprising such organic compounds which, on exposure to light, become.altered in their adhesiveness or their capability of reception for dust-like substances, such as pigments and so forth. The alteration in question may reside either in an increase or in a diminution of the adhesiveness under the influence of the light. According to the direction in which the alteration takes place, positives or The light sensitive materials according to the invention are sensitized by means of such light sensitive nitro-compounds, as possess one or more hydroxyl groups, for example in the form of an aliphatic alcohol residue. The light sensitive compounds are obtained by way of example by condensing an aromatic nitro-aldehyde with a polyhydric aliphatic alcohol. Such condensation products are known under the name acetals. Suitable compounds are o-nitrobenzylideneglycerine, o-nitrobenzylidenedulcitol and the like.

The light sensitive organiccompounds may be applied to or coated on bases of'the most varied 40 kind, for example, metal, cloth, film, glass, paper and so forth. When supports capable of tanning are employed, it is possible in certain circumstances to cause in addition to the alteration of the light sensitive layers themselves simultaneous alterations of the substance of the support.

According to the process of the present invention the described light sensitive materials are exposed to light under a suitable pattern. By 50. this exposure the adhesiveness of the material is altered at the places struck by the light. The finishing of the obtained prints after exposure is generally efiected solely by dusting-on. the material. Any particular after-treatment after exposure with solvent means for the purpose of negatives which, as concerns the image, is not benzylidenedulcitol.

swelling, moistening or the like, such as has to be employed in other known dusting-on processes, is, in general, not necessary.- This constitutes a great advance as compared with known dusting-on processes. It may in some cases be advantageous to' treat the dusted-on prints with solutions in order to remove possible harmful undecomposed nitro-compounds or coloured decomposition products. For the dusting-on process colouring matters of various quite different classes may be employed, but insoluble colouring matters are particularly suitable.

The following examples when taken with the accompanying self-explanatory drawing depicting' a section through a light sensitive material according to the present invention serve to. illustrate the invention:

(1) A concentrated solution of o-nitrobenzylideneducitol (see Chem. Zentralblatt 1934, I, page'1189, formula 1) in dioxan is applied to gelatinized paper and exposed. After the exposure the paperis dusted over with Vermilion or cinnabar. The reproduction obtained from a positive is'also positive.

(2) A concentrated solution of o-nitrobenzylideneglyceiine (see Chem. Zentralblatt 1930 I,

page 972 in ether is applied to gelatinized paper.

deneglycerine in ether is applied to gelatinized p p r and after the exposure tiiphenylmethane is dusted on. A colourless positive is obtained transparent to ultra-violet rays.

In Examples 2 and 3 above, the o-nitrobenzylideneglycerine may also be itself applied to the support without dissolving it in a solvent means.

(4) Mixtures of different quantities of o-nitrobenzylidenedulcitol and o-nitrobenzylideneglycerine are applied to gelatinized paper. After the exposure indigo is dusted on. In this case the reproduction obtained from a negative is also a negative. It is also possible to dust on logwood (red wood) extract and in this case a positive is obtained from. a negative.

I claim: 1. Light sensitive material comprising a base and thereon, as light sensitive matter, anecetal series and an aliphatic polyhydric alcohol.

2. Light sensitive material comprising a base and thereon, as light sensitive matter, o-nitro- 3. Light sensitive material comprising a base and thereon, as light sensitive matter, o-nitrobenzylideneglycerine.

4. Process for the production of prints and 5 the like which comprises exposing a material sensitized to light with anacetal of an aromatic nitro-aldehyde of the benzene series and an allphatic polyhydric alcohol to the action of light in a, definite pattern to thereby change the ad- 10 hesiveness oi the parts exposed to light and dusting said material with a coloring agent.

5. Process for the production of prints and the like which comprises exposing a material sensitized to light with an acetal of an aromatic 15 o-nitro-aldehyde of the benzene series and an 6. Process for the production oi prints and the like which comprises exposing a. material sensitized to light with o-nitrobenzylideneduldtol to the action or light in a definite pattern to thereby change the adhesiyeness of the parts exposed to light and dusting said material with a coloring agent.

'1. Process for the production of prints and the like which comprises exposing a material sensitized to light with o-nitrobenzylideneglycerine to the action of light in a definite pattern to thereby change the adhesiveness of the parts exposed to light and dusting said mterial with a coloring agent.

8. Light sensitive nnterial comprising a, base and thereon, as light sensitive matter, an acetal of an aromatic o-nitro-aldehyde or the benzene series and an aliphatic polyhydric alcohol.

GUSTAV xbann 

